Thickened inorganic oxidizer salt explosive slurry sensitized with a soluble polyflavonoid



United States Patent 3,397,096 THICKENED INORGANIC OXIDIZER SALT EX-PLOSIV E SLURRY SENSITIZED WITH A SOLU- BLE POLYFLAVONOID Errol LintonFalconer, St. Hilaire, Quebec, and Cornelius James Noel Kelly, Beloeil,Quebec, Canada, assignors to Canadian Industries Limited, Montreal,Quebec, Canada No Drawing. Filed Nov. 20, 1967, Ser. No. 684,538 Claimspriority, application Canada, Dec. 6, 1966, 977,354 8 Claims. (Cl.149--39) ABSTRACT OF THE DISCLOSURE The sensitivity of slurry explosivecompositions comprising inorganic oxygen-supplying salts, a fuel, athickener and a liquid carrier is substantially improved byincorporating in the composition a soluble polyflavonoid and a commonsolvent for the polyflavonoid and the inorganic salt.

This invention relates to explosive compositions comprising essentialyan inorganic oxygen-supplying salt, a sensitizer, a fuel, a thickenerand a mutual solvent for the inorganic salt and the sensitizer. Inparticular, the invention relates to a means whereby the sensitivity ofsuch explosive compositions may be substantially improved.

Explosive compositions comprising an oxygen-supplying salt such as, forexample, ammonium nitrate, and a sensitizer and/or fuel together with afluid solvent, disperser or carrier such as water, are known. Thesecompositions are commonly referred to as slurry explosive compositionsor, more generally, as slurry explosives. Such slurry explosives mayrange in degree of firmness or consistency from highly viscous,plastic-like extrudable compositions to less viscous pumpable orpourable fluidlike mixtures.

Slurry explosive compositions of the aforementioned types normallycontain as essential ingredients widely known sensitizing and powerenhancing materials and fuels such as, for example, finely divided lightmetal, finely divided carbon and the like. In some cases, it isadvantageous to add a self-explosive ingredient such as particulate TNT,PETN, or smokeless powder to further improve the sensitivity or strengthor both of the slurry explosives and thereby insure detonation andpropagation. A wide range of such compositions are now known to the art.

For optimum reliability the known sensitizers employed in slurryexplosives are either self-explosives or relatively expensive materialssuch as very finely divided light metal powders. Without suchsensitizers, these slurry explosive compositions tend to be detonableonly in large diameter charges with large primers. It has thus beennecessary for the manufacturer of explosives to employ relatively largequantities of sensitizing material and fuel in slurry explosives inorder to insure detonation and propagation. Such compositions, as wellas being relatively expensive, are hazardous to handle and requirespecial and costly precautions in manufacture, transportation, storageand use. Slurry explosive compositions containing self-explosives are,in turn, in most jurisdictions subject to regulatory restrictions intransportation and storage. Those that contain reactive sensitizers suchas, for example, paintfine aluminium powder, tend to deteriorate andlose sensitivity on storage.

It has now been found that the aforementioned disadvantages may beovercome by employing as a sensitizer in slurry explosive compositions asoluble polyfiavonoid.

It is, therefore, an object of the present invention to provide a meanswhereby the sensitivity of a slurry explosive composition may beincreased.

Another object of the invention is to provide a slurry explosivecomposition which may be detonated in boreholes of small diameter.

Another object of the invention is to provide a sensitive slurryexplosive composition which is devoid of any self-explosives or otherhazardous material.

A further object of the invention is to replace the known reliablesensitizers in slurry explosive compositions with a sensitizer that ismuch less costly and easily available.

These and other objects of the invention will become apparent from aconsideration of the following description and claims.

The improved explosive composition of this invention comprisesessentially at least one inorganic oxygen-supplying salt, at least onesoluble polyflavonoid, a fuel, a thickener and a mutual solvent, usuallywater, for the inorganic salt and the polyfiavonoid.

The addition of a soluble polyflavonoid to a slurry explosivecomposition has the surprising and desirable effect of substantiallyincreasing the sensitivity of the composition.

It is thus now possible to prepare useful and powerful, slurry explosivecompositions which, though devoid of any self-explosive ingredient, maybe detonated with ease in boreholes of small diameters. It is similarlynow possible to prepare such compositions even containing additionalsensitizing material such as, for example, finely divided aluminium,aluminium, alloy, silicon, ferrosilicon or ferrophosphorus orself-explosives which are more reliable to detonation and propagationthan heretofore and which may be detonated in smaller diameter and withthe use of smaller priming charges that has heretofore been possible.

Preferred blasting slurry explosive compositions of this inventioncontain from 30 to by weight of at least one inorganic oxygen-supplyingsalt, from 0.1 to 25% by weight of a soluble polyfiavonoid, from 1 to30% by weight of a mutual solvent for the inorganic salt and thepolyflavonoid, from 0.1 to 10% by weight of thickener and from 0 to 40%by weight of fuel, the proportions of the ingredients being such thatthe oxygen balance of the total composition is from +15 to -35 grams ofoxygen per grams of finished explosive.

A preferred inorganic oxygen-supplying salt for inclusion in theexplosive compositions of this invention is ammonium nitrate. It is insome cases advantageous to replace some, suitably up to 50% or even upto 90%, of the ammonium nitrate by other metal nitrates such as sodium,barium, potassium and calcium nitrates. The particle size of theinorganic oxygen-supplying salts is not critical and powdered,granulated, or prilled forms may be used and part of the salts may bepredissolved in all or part of the solvent.

A preferred mutual solvent for the oxidizing salt and the solublepolyflavonoid is water. However, quite large proportions of the watermay be replaced by organic solvents such as formamide, dimethylsulfoxide and the lower glycols and alcohols. These solvents are polarliquids, readily miscible with water in all proportions and areeffective solvents for ammonium nitrate and other inorganic salts. Thereplacement of water is limited only by the lack of solubility of thepolyflavonoid in solvent mixtures of low water content.

Where employed, the aluminium or aluminium alloy or other energeticmetal or metalloids suitable for use in the explosive composition ofthis invention must be in finely divided form and may most suitablyrange from a fine dust to a form not coarser than that which will passthrough a size 6 Tyler mesh screen. For example, relatively inexpensiveair-atomized aluminium powder, shredded foil or granules made fromreclaimed scrap are suitable types. The use of the expensive paint-finealuminium is not required to achieve high sensitivity in the explosivecomposition of this invention.

Useful particulate self-explosives which may be used in the explosivecomposition include, for example, trinitrotoluene (TNT) pentaerythritoltetranitrate (PETN), cyclotrimethylenetrinitramine (RDX), composition B(mixture of TNT and RDX), pentolite (mixture of PETN and TNT), smokelesspowder, nitrocellulose, nitrostarch and mixtures of these.

The gel-forming or thickening polysaccharides employed in the aqueousslurry form of the explosive of the invention are preferablymannogalactans such as guar gum or carab seed. Guar gum of theself-cross-linking type recently made available on a commercial scalemay be suitably employed. Where either dimethyl sulfoxide or formamideis employed alone as the mutual solvent in the slurry, hydroxyethylcellulose may be used as a suitable thickener. Where -dimethylsulfoxidc, formamide or ethylene glycol is used in combination withwater, guar flour, tamarind flour or starch are suitable thickeners. Anumber of modified and synthetic materials useful as thickeners can beselected which are appropriate to the solvents employed and will beobvious to those skilled in the art.

Metallic chromates suitable for use as cross linking agents for thepolysaccharides in aqueous slurries are the same as those disclosed inCanadian Patent No. 729,- 555 issued on Mar. 8, 1966, that is, ametallic chromate selected from the group consisting of sodium andpotassium dichromate and zinc and barium chromate.

The soluble polyflavonoid sensitizers are polyphenolic extracts fromwood or bark and are commercially available as a sodium salt and sold asthe trademarked product Rayfio-C by Rayonier Inc., New York. Thepolyflavonoid useful as sensitizers in the composition of the inventionmay be characterized by the resultant persistant head of foam which isformed when from 0.5% to 2.0% by weight of polyflavonoid is stirred intoan aqueous solution saturated in nitrates of ammonia and sodium. Thepolyflavonoid may be employed either as a dry powder or alternatively asa solution. Where a polyflavonoid solution is employed, for example, anaqueous solution, the water of solution may be employed as all or partof the aqueous medium of the explosive composition.

The explosive composition may be prepared by processes well known in theart employing simple mixing procedures, the soluble polyflavonoidsensitizer being added at any convenient stage in the manufacture. Thepolyflavonoid sensitizer may similarly be employed where a slurryexplosive composition is prepared for use at the blasting site by meansof the now well known slurry mix truck.

The following examples and table illustrate the improved explosivecomposition of this invention but the latter is in no manner to belimited in scope to the embodiments described.

EXAMPLE 1 A series of six viscous slurry compositions were preparedcontaining as essential ingredients, particulate organic explosives,oxygen-supplying salts, water and thickeners. To three of thecompositions was also added a known sensitizer, sodium lignosulphonate.To one composition was additionally added powdered aluminium. Four ofthe compositions had added thereto a polyflavonoid sensitizer. Thecompositions were packaged in 1% inch and 2 /2 inch diameter cartridgesand exposed to initiation by various means. The compositions devoid ofpolyflavonoid failed to detonate. The results are summarized in thetable below, the quantities shown being expressed as percent by weightof the total.

Aluminium powder Zn Chromate (stabilizer) Tamarind flour Guar flourSolium lignos ulphonate- Polytlavonoid (sod. salt) 5 Z-ethyl hexanol l 2W or 3.5 3.5 4.5 4.2 9.2 9.2 Density (gm./cc.) 1.31 1.27 1.42 1. 6 1. 341.20 Cartridge diameter, in 1 1% 1% 1% 2% 2% 1 Employed to eliminate anylarge unstable air bubbles in mix. 2 No. 8 Cap failed.

3 One No.8 Cap fired.

4 No. 12 Cap failed.

5 One N0. 12 Cap fired.

@ 160 gm. pentolite fired.

It can be noted from the results shown in the table that Mixes 1 and 3,devoid of polyflavonoid yet containing a known sensitizer sodiumlignosulphonate, failed to detonate while mixes 2 and 4 of similarcomposition and containing the polyflavonoid sensitizer were deionatedwith ease. Mix 5, devoid of any self-explosive ingredient Was madesensitive by the addition of a small quantity of polyflavonoid.

Primary charge EXAMPLE 2 A slurry explosive composition was preparedcontaining as essential ingredients 53.0% by weight of ammonium nitrate,18% by weight of sodium nitrate, 1.2% by weight of urea, 0.8% by weightof tamarind flour, 18% by weight of particulate aluminium and 9.0% byweight of water. The composition was packaged in 2 /2 inch diametercartridges and exposed to detonation by means of a 160 gm. pentoliteprimer. The composition failed to detonate. A similar compositioncontaining 1.5% by weight of a polyflavonoid as a replacement for a likequantity of ammonium nitrate was easily detonated with a similar primerat a detonation velocity of 3580 meters/ second.

EXAMPLE 3 EXAMPLE 4 A slurry explosive composition was preparedcontaining as essential ingredients 62.5% by weight of ammonium nitrate,12.6% by weight of sodium nitrate, 7.5% by weight of sulphur, 0.8% byweight of guar flour, 12.6% weight of water and 4.0% by weight of apolyflavonoid. The composition had a prepared density of 1.21 gm./cc.and detonated in a 2%. inch diameter cartridge using a primer of gms. ofpentolite.

EXAMPLE 5 A slurry explosive composition was prepared containing asessential ingredients 69.4% by weight of ammonium nitrate, 15.0% byweight of powdered aluminium, 0.6% by weight of hydroxyethyl cellulose(thickener), 12.0% by weight of dimethyl sulfoxide, 2.0% by weight ofwater and 1.0% by weight of a polyflavonoid. The composition had aprepared density of 1.40 gm./cc. and detonated in a 2 /2 inch cartridgeusing a primer of 320 gms. of pentolite.

As may be seen from the results shown in the preceding examples andtable, the addition of a soluble polyflavonoid to a slurry explosivecomposition has the surprising effect of substantially increasing thesensitivity of the compositions. Slurry explosives of this type havingan oxygen balance outside the range of to grains of oxygen per 100 gramsof finished explosive make very uneconomical use of the availableenergy. It is preferred, therefore, that quantities of polyflavonoidsensitizer and fuel used be such that the oxygen balance of thecomposition is within the range +15 to ---35.

It 'will be appreciated by those skilled in the art that the principaladvantage to be enjoyed through the use of the polyflavonoid sensitizedslurry explosive compositions of the invention lies in the utilizationof non-self-explosive slurry composition. That is, slurry compositionscomprising oxygen-supplying salts, a solvent for the oxygen-supplyingsalts .and a fuel may now, by the addition of a suitable quantity of apolyflavonoid, be employed as practical and reliable commercialexplosives posses-sing the additional advantages of low cost and greathandling safety. Where it is desired to include in such compositionsadditional strength ingredients such as powdered light metal fuels orself-explosives, the use of the polyflavonoid sensitizers providescompositions which may be detonated in smaller diameter charges or withlower strength primers than has heretofore been possible.

The polyflavonoid sensitizers provide an additional function incontrolling the density of the explosive compositions since they areeffective agents in preventing or arresting the dissipation of minutebubbles of air which have been entrained or occluded in the slurrymixture. Such air bubbles are normally incorporated in slurry explosivecompositions by the lifting and folding of the mixture which occursduring the mechanical mixing of the ingredients or, alternatively, airis entrapped into the mixture in the voids of the dry ingredients. Suchcontrol of density is useful in permitting different loading andcartridgin'g densities.

What we claim is:

1. An explosive composition comprising essentially at least oneinorganic oxygen-supplying salt, a soluble polyflavonoid, a mutualsolvent for the inorganic oxygen-supplying salt and the solublepolyflavonoid, a thickener and a fuel, the proportions of theindgredients being such that the oxygen balance of the total compositionis from about +15 to about -35 grams of oxygen per 100 grams of finishedexplosive.

2. An explosive composition as claimed in claim 1 wherein the fuel isselected from the group consisting of carbonaceous material, particulateorganic explosives, particulate light metal or metalloids, sulphur,carbon, urea and mixtures thereof.

3. An explosive composition as claimed in claim 1 wherein the mutualsolvent is water.

4. An explosive composition as claimed in claim 1 wherein the mutualsolvent comprises a mixture of water and a miscible organic solventselected from the group consisting of formamide, dimethyl sulfoxide,lower glycols and alcohols, the proportions being such as to permit asolubility of not less than 5 parts of polyflavonoid per 100 parts ofthe solvent mixture.

5. An explosive composition as claimed in claim 1 wherein the oxygensupplying salt is selected from the group consisting of the nitrates ofammonia, sodium, potassium, barium, calcium and mixtures thereof.

6. An explosive composition as claimed in claim 1 wherein the solublepolyflavonoid is present as its sodium salt.

7. An explosive composition as claimed in claim 2 wherein theparticulate organic explosive is selected from the group consisting oftrinitrotoluene, pentaerythritol tetranitrate,cyclotrimethylenetrinitramine, mixture of trinitrotoluene andcyclotrimethylenetrinitramine, mixture of pentaerythritol tetranitrate,smokeless powder, nitrocellulose, nitrostarch and mixtures thereof.

8. An explosive composition comprising essentially between about 30% andabout by weight of an inorganic oxygen-supplying salt, between about0.1% and 25% by weight of a soluble polyflavonoid, from about 1% toabout 30% by weight of a mutual solvent for the inorganicoxygen-supplying salt and the soluble polyflavonoid, from about 0.1% toabout 10% by weight of a thickener and from 0 to 40% by weight of afuel, the oxygen balance of the total composition being from about +15to about '35 grams of oxygen per grams of finished explosive.

BENJAMIN R. PADGETT, Primary Examiner.

S. J. LECHERT, In, Assistant Examiner.

